This invention relates to a system for heating a small volume of liquid and more particularly to an immersion heating system used to warm beverages and the like in small containers especially for single servings.
Currently available immersion heaters provide a coil or other standard means for heating a volume of liquid. Typically, the coil or heating element is constructed of a material with electrical resistivity sufficiently high so that the element becomes hot as current passes through it. When immersed in a liquid the energized heating element warms the surrounding liquid. As long as the element is energized, the liquid temperature will continue to increase until boiling and complete evaporation occur. At this point the heating element will often overheat and become permanently nonfunctional. None of the currently available immersion heaters provide protection against this problem.
Furthermore, none of the known immersion heaters provide protection against contact of the heating element with either the user or the surrounding environment. The exposed heating element creates a dangerous condition for the careless consumer which may result in a superficial yet painful burning of the hands. Moreover, the exposed heating element poses a problem in that immediately after use, the consumer must exercise care in the choice of a resting place for the heater as the exposed element may burn the surface on which it is placed. Similarly, currently available immersion heaters that suspend from the edge of the container may burn, disfigure or destroy the interior surface of the container as well.
In addition, most immersion heaters are thermodynamically inefficient insofar as thermal energy transferred to the liquid is lost via the open top of the container. In short, the problem has been to provide an immersion heater that is efficient and yet safe to operate.